The problem can be corrected by upgrading the affected package to version 1:0.93.94-4ubuntu1.1. In general, a standard system upgrade is sufficient to effect the necessary changes.

Details follow:

Several vulnerabilities have been found in the XPM image decoding functions of the LessTif library. If an attacker tricked a user into loading a malicious XPM image with an application that uses LessTif, he could exploit this to execute arbitrary code in the context of the user opening the image.

Ubuntu does not contain any server applications using LessTif, so there is no possibility of privilege escalation.

Please note that this update only fixes lesstif2. The older lesstif1 version is also affected. A proper fix for lesstif1 will still take some time and will be done in a separate USN. However, no Ubuntu application uses lesstif1, so this could only affect you if you use third party software which depends on this library.